Pressure-sensing guidewire and sheath

ABSTRACT

A pressure sensing device is provided that can monitor and measure pressure at two points in a vessel or artery without moving the outer sheath or catheter of the device. The outer sheath or catheter includes two spaced apart openings that may be positioned in a vessel or artery on opposing sides of an occlusion. The device also includes an inner elongated tube with at least one opening. The inner elongated tube is slidable with respect to the outer sheath or catheter thereby permitting the opening of the elongated tube to be moved into selective registration with one of the openings of the outer sheath. A pressure measurement may be taken through one of the openings in the outer sheath by aligning the opening of the elongated tube with said opening and, then, a second pressure reading may be taken by sliding the elongated tube within the outer sheath so that the opening of the elongated tube is in registry with the other opening of the tubular sheath. As a result, pressure measurements at two points in a vessel or artery may be taken without moving the outer sheath or catheter.

FIELD OF THE INVENTION

[0001] The present invention generally relates to intravascular medicaldevices and methods for monitoring and measuring fluid pressure. Morespecifically, the present invention relates to intravascular diagnosticdevices and methods for monitoring and measuring fluid pressure atselected points in coronary vessels or arteries. Still morespecifically, the present invention relates to intravascular devices andmethods for monitoring and measuring fluid pressure at selected pointsin an artery on opposite sides of an occlusion or partial blockage.Those skilled in the art will recognize the benefits of applying thepresent invention to similar fields not discussed herein.

BACKGROUND OF THE INVENTION

[0002] Angioplasty procedures have gained wide acceptance in recentyears as efficient and effective methods for treating many types ofvascular disease. In particular, angioplasty is widely used for openingstenosis or occlusions in the coronary arteries, although it is alsoused for the treatment of stenosis in other parts of the vascularsystem.

[0003] The most widely used form of angioplasty makes use of a dilationcatheter which has an inflatable balloon at its distal end. Inflation ofthe balloon at the site of the occlusion causes a widening of the vesselor artery to reestablish an acceptable blood flow through the vessel orartery.

[0004] It often is desirable to determine the severity of the occlusionin order to properly choose a dilation catheter or to make adetermination as to whether treatment is required. Various techniqueshave been used to determine the severity of the occlusion. One way ofdetermining the severity of the occlusion is to measure pressure bothproximal to and distal of the occlusion.

[0005] Specifically, referring to FIG. 1 (which does not illustrate aprior art device, but which instead illustrates one disclosedembodiment), two occlusions 11, 12 are shown in an arterial wall 13. Indetermining the severity of the occlusion 11, knowledge of the ratio ofthe pressures P₂:P₁ is important. A ratio of P₂:P₁ of less than 0.75 isindicative of an occlusion requiring treatment and a ratio of P₂:P₁ ofgreater than 0.75 is indicative of an occlusion not requiring treatment.Similarly, with reference to the occlusion shown at 12 in FIG. 1, if theratio P₃:P₂ is less than 0.75, it would be an indication that theocclusion 12 would require treatment. If the ratio P₃:P₂ is greater than0.75, it would be an indication that the occlusion 12 does not requiretreatment.

[0006] Devices that are used for this purpose include catheter-likemembers with some type of pressure-sensing device incorporated therein.One known device measures the pressure as a function of the deflectionof a diaphragm located at the proximal end of the catheter. One problemassociated with currently available pressure-sensing devices is thatthey are unable to measure pressure at points both proximal and distalto the occlusion without moving the device. When the device or catheteris moved, it can often cause physical changes to the occlusion therebyaffecting the second pressure measurement. Further, unnecessary movementof the catheter can dislodge a portion of the plaque that forms theocclusion. Further, because it is often difficult to insert catheters incoronary arteries and other vessels, physicians are often reluctant tomove a catheter in a proximal direction once the catheter is inposition. Hence, once a physician inserts a catheter past the point ofocclusion, the physician is often reluctant to move the catheter to apoint proximal to the occlusion to take a pressure measurement if acatheter must be moved back to a location distal to the occlusion at alater time in the procedure.

[0007] Accordingly, there is a need for an improved intravascularpressure-sensing device which can monitor and measure pressure atmultiple points along a vessel or artery without moving the device.Still further, there is a need for an intravascular pressure-sensingdevice which can monitor and measure pressure at multiple points along avessel or artery simultaneously.

[0008] It would be desirable to make use of both multi-pointintravascular pressure sensing devices and methods in order to provide aphysician with sufficient diagnostic information to make a determinationas to whether the occlusion should be treated. The ideal multiple pointpressure measurement device would be accurate, low profile, flexible andhave a fast response time. Both the cost and ease of use of the completesystem needs to be considered as well to produce a commerciallysuccessful product. Presently available devices are not capable ofsimultaneously meeting these various requirements.

SUMMARY OF THE DISCLOSURE

[0009] The present invention overcomes the deficiencies of the prior artby providing a pressure monitoring and measuring device that comprisesan elongated tube having an opening. The elongated tube is slidablyreceived in a tubular sheath. The tubular sheath comprises at least twospaced apart openings. The elongated tube is slidably within the tubularsheath thereby allowing the opening of the elongated tube to beselectively aligned with both openings of the tubular sheath. In use,the elongated tube is positioned within the tubular sheath so that itsopening is aligned with one of the openings of the tubular sheath. Apressure measurement is made in this position. Then, the elongated tubeis moved within the tubular sheath so that its opening is aligned withthe other opening of the tubular sheath. A second pressure measurementis made in this position.

[0010] In use, the above described embodiment would be introduced into apatient's vasculature in advance to a point whereby one of the openingsof the tubular sheath is disposed distal to an occlusion and the otherof the openings in the tubular sheath is disposed proximal to theocclusion. In this way, the elongated tube can be manipulated to take apressure reading at points both distal and proximal to the occlusionwithout moving the tubular sheath.

[0011] In another embodiment, a method for monitoring and measuringpressure on opposing sides of an occlusion is disclosed. The methodcomprises the steps of providing a pressure measuring device comprisingan elongated tube having an opening. The elongated tube is slidablyreceived in a tubular sheath. The tubular sheath comprises either atleast two spaced apart openings or one elongated opening. The elongatedtube has a proximal end connected to a pressure transducer. The methodfurther includes the step of inserting the pressure measuring deviceinto a vessel having an occlusion until one of the openings of thetubular sheath is disposed on one side of the occlusion and the otheropenings of the tubular sheath is disposed on an opposite side of theocclusion. The method further includes the steps of aligning the openingof the elongated tube with one of the openings of the tubular sheath ora portion of the elongated opening on one side of the occlusion,measuring the pressure at the one opening of the tubular sheath throughthe elongated tube, aligning the opening of the elongated tube with theother openings of the tubular sheath or a portion of the elongatedopening on an opposite side of the occlusion, and measuring the pressureat the other opening of the tubular sheath through the elongated tube.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a partial sectional schematic view illustrating a vesselor artery with two occlusions and the distal end of a disclosed pressuremeasuring device inserted into the vessel or artery and wherein theelongated tube of the pressure measuring device is in a first positionto measure a pressure P₃ distal to the occlusion 12.

[0013]FIG. 2 is another partial sectional schematic view of the arteryand device shown in FIG. 1 but with the elongated tube of the devicemoved to a second position to measure a pressure P₂ proximal to theocclusion 12 and distal to the occlusion 11.

[0014]FIG. 3 is another partial sectional schematic view of a vessel orartery and the device shown in FIG. 1 but with the device moved to athird position for measuring the pressure P₁ proximal to the occlusion11.

[0015]FIG. 4 is a partial elevational view of the tubular sheath of thepressure measuring device shown in FIG. 1.

[0016]FIG. 5 is a partial elevational view of the elongated tube of thepressure measuring device shown in FIG. 1.

[0017]FIG. 6 is an end sectional view taken substantially along line 6-6of FIG. 1.

[0018]FIG. 7A is an end sectional view of an alternative pressuremeasuring device taken substantially along line 7A-7A of FIG. 7B

[0019]FIG. 7B is a partial side sectional view of the pressure measuringdevice shown in FIG. 7A.

[0020]FIG. 8 is a partial sectional view of a proximal end of adisclosed pressure measuring device.

[0021]FIG. 9 is a partial elevational view of another alternativetubular sheath.

[0022]FIG. 10 is a partial elevational view of another elongated tube.

[0023]FIG. 11 is a partial sectional view illustrating a connectionmechanism between the elongated tube and tubular sheath of one disclosedembodiment.

[0024]FIG. 12 is a partial sectional view illustrating a connectionmechanism between the elongated tube and tubular sheath of anotherdisclosed embodiment.

[0025]FIG. 13 is a partial sectional view illustrating a connectionmechanism between the elongated tube and tubular sheath of yet anotherdisclosed embodiment.

[0026]FIG. 14 is a partial sectional view illustrating a connectionmechanism between the elongated tube and tubular sheath of anotherdisclosed embodiment.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0027] Turning to FIG. 1, a vessel or artery 13 which includesocclusions 11 and 12. As discussed above, it is important for thephysician to know the arterial pressure both proximal and distal to theocclusions 11 and 12 in order to make a determination as to whether theocclusions 11 and 12 require treatment. To make the determination withrespect to the occlusion 12, the physician needs to know the pressuresP₂ and P₃. In order to make a determination as to the occlusion 11, thephysician needs to know the pressures P₁ and P₂.

[0028] Still referring to FIG. 1, a pressure measuring device 14 hasbeen inserted into the vessel or artery 13 so that its distal end 15 isdisposed past or distal to the occlusion 12. The device 14 includes anouter tubular sheath 16 having two openings 17, 18. The device 14 hasbeen positioned in the vessel 13 so that the opening 17 is proximal tothe occlusion 12 and the opening 18 is distal to the occlusion 12. Aspring tip is shown schematically at 19. It will be understood that thespring tip 19 can be of a conventional type, two examples of which areshown and described in U.S. Pat. Nos. 5,964,714 and 5,860,938, both ofwhich are assigned to the assignee of this application and which areincorporated herein by reference.

[0029] The device 14 further includes an elongated tube 21 that isslidably received within the tubular sheath 16. The elongated tubeincludes at least one opening 22. The elongated tube 21 can be movedwith respect to the tubular sheath 16 so that the opening 22 of theelongated tube 21 can be moved from a position in substantial registrywith the opening 18 of the tubular sheath 16 as shown in FIG. 1 to theposition shown in FIG. 2 where the opening 22 of the elongated tube 21is in substantial registry with the opening 17 of the tubular sheath 16.In the position shown at FIG. 1, the device 14 can measure the pressureP₃, i.e., the pressure distal to the occlusion 12. In a preferredembodiment, the elongated tube 21 is rotationally aligned with respectto the tubular sheath 16. In alternative embodiments, the elongated tube21 may be slidably received within the tubular sheath 16, but fixed in asingle position, for example, by way of a key and keyway, so they maynot be rotatably moved relative to each other.

[0030] The device 14 can be manufactured so that the elongated tube 21is frictionally received within the tubular sheath 16. That is, thedevice 14 can be constructed so that the inside surface 23 of thetubular sheath 16 engages the outside surface 24 of the elongated tube21 so that fluid communication between the two surfaces is substantiallyprevented. If the device 14 is constructed in this way, a closed end forthe tubular sheath 16 is not necessary. As shown in FIG. 8, the proximalend 26 of the elongated tube 21 extends outward from the proximal end 27of the tubular sheath 16. The proximal end 26 of the elongated tube 21is received in a pressure transducer 28. A seal 29 is provided at theproximal end 27 of the tubular sheath 16, which allows the elongatedtube 21 to slide with respect to the tubular sheath 16 without allowingfluid to pass between the outside of the elongated tube 21 and thesheath 16.

[0031] Returning to FIG. 1, the device 14 is in a position where thepressure P₃ can be measured. Turning to FIG. 2, the elongated tube 21has been shifted with respect to the tubular sheath 16 so that theopening 22 of the elongated tube 21 is now in registry with the opening17 of the tubular sheath 16. In the position shown in FIG. 2, thepressure P₂ can be measured without moving the tubular sheath 16. Forthe embodiment illustrated in FIGS. 1-3, in order to measure thepressure P₁ proximal to the occlusion 11, the device 14 is movedlaterally to the left or in a proximal direction so that either theopening 17 or opening 18 of the tubular sheath 16 is proximal to theocclusion 11 and the elongated tube 21 is shifted accordingly. As shownin FIG. 3, movement of the tubular sheath 16 is minimized and theopening 17 of the tubular sheath is moved to a position distal to theocclusion 11 and no shift of the elongated tube with respect to thetubular sheath 16 is necessary.

[0032] Turning to FIGS. 4, 5 and 8, it will be noted that the proximalend 26 of the elongated tube 21 may include a plurality of markings 31,32 (see FIG. 8). Because the proximal end 26 of the elongated tube 21extends outward from the proximal end 27 of the tubular sheath 16, themarkings can be useful to the physician for lining up the opening 22 ofthe elongated tube 21 with the openings 17, 18 of the tubular sheath 16.In the examples shown in FIGS. 4, 5 and 8, a mark 32 can be provided atthe proximal end 21 or at the seal 29 when the opening 22 of theelongated tube 21 is in registry with the opening 17 of the tubularsheath 16. Further, a second mark 31 can be provided that is alignedwith the proximal end 27 of the tubular sheath 16 or seal 29 when theopening 22 of the elongated tube is in registry with the opening 18 ofthe tubular sheath 16. Other positioned indicators will be apparent tothose skilled in the art.

[0033] Further, referring to FIGS. 4 and 5, radiopaque markers 33 a, 33b and 33 c may be provided in the form of a coil or band loaded into thesheath 16 or tube 21 which can viewed by positions using fluoroscopy.

[0034] Turning to FIGS. 6 and 7, it will be noted that a sectional viewof the embodiment 14 shown in FIGS. 1-5 and 8 is shown in FIG. 6 while asectional view of an alternative embodiment 35 is shown in FIG. 7. Inthe alternative embodiment 35, the tubular sheath 36 includes a wall 37that extends along the length of the sheath 36 thereby creating twoseparate lumens 38, 39. An opening 43 in the sheath 36 is in alignmentwith the lumen 38 and an opening 44 is provided in the sheath 36 whichis in alignment with the lumen 39. With the openings 43, 44 beinglaterally spaced apart, pressures at points proximal and distal to anocclusion can be measured simultaneously. That is, if the device 35 ispositioned within a vessel or artery so that one of the openings 43 isproximal to an occlusion and the other of the openings 44 is distal tothe occlusion, and two elongated tubes are provided in the positionshown in FIG. 7, simultaneous pressure measurements at points bothproximal and distal to the occlusion can be made.

[0035]FIG. 9 is a partial view of a tubular sheath 50 with a singleelongated slot or opening 51. The opening 51 is sufficiently long enoughso that it can traverse a typical occlusion thereby leaving portions ofthe opening 51 at points both proximal and distal to the occlusion. Anelongated tube 52 as shown in FIG. 10 is inserted into the sheath 50 andthe small opening 53 can be moved to points proximal and distal to theocclusion for communicating a pressure reading through the opening 51.

[0036] FIGS. 11-14 illustrate various mechanisms for connecting theelongated tubes 21 a-21 c to the tubular sheaths 16 a-16 d. In FIG. 11,the elongated tube 21 a is equipped with a wedge portion 60 that isdisposed distal to a radially inwardly extending section 61 of thetubular sheath 16 a. The wedge 60 can be formed by grinding the tube 21a or additional material can be applied to the wedge section 60 such asa polymeric sleeve for purposes of enlarging the wedge section 60. InFIG. 12, a detent 62 is provided on the tubular sheath 16 b which isreceived in a recess 63 in the elongated tube 21 b. In FIG. 13, asimilar wedge structure 64 is formed in the elongated tube 21 c. Thewedge 64 is received in a recess 65 in the tubular sheath 16 c that isbound by a radially inwardly extending restricted portion 66 and adetent 67. In FIG. 14, a similar wedge structure 68 is provided on theelongated tube 21 d and is disposed between a restricted portion 70 ofthe tubular sheath and complimentary threads 71, 72 disposed on thetubular sheath 16 d and elongated tube 21 d, respectively. Theembodiments shown in FIGS. 11-13 are free to rotate with respect to eachother while the threaded connection provided by the thread 71, 72 ofFIG. 14 provide a more secure connection.

[0037] Both the sheath and tube of the disclosed pressure measuringdevices can be made from a variety of materials, which will be apparentto those skilled in the art. The sheaths are preferably made frommaterial suitable for the manufacture of pressure measuring guidewires.Such materials are commonly metallic, but it is anticipated that otherpolymeric materials may also be suitable for fabricating the sheath. Theelongated tubes may also be made from metallic or polymer materials.Such suitable metallic or polymer materials include, but are not limitedto polymer materials such as Pebax™, Arnitel™, polybutyleneterephthalente (PBT), polyoxymethylene (POM), polyethylene (PE),polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE),polyvinyl chloride (PVC), thermoplastic elastomer (TPE), polyamide andNylon™ and metallic alloy materials such as Inconel 617™, Inconel 625™,Hastelloy S™, Hastelloy X™, Nimonic 90™, Incoloy 800™, MP35-N Elgiloy™,304LV™, 316 LVM™, Aermet 100™, Aermet 310™, CRB-7™, Custom 450™, Custom455™, Custom 465 m™, NiMark 250™, NiMark 250 NCO™, NiMark 300™, Nickel200™, 304LV™, 316 LVM™, 321™, 347™, Aermet 100™, Aermet 310™, Haynes214™, Haynes 230™, Inconel 600™, Inconel 601™, Inconel 617™, Inconel625™, RA 333™, Hastelloy B™, Hastelloy N™, Hastelloy S™, Hastelloy W™,Hastelloy X™, Hastelloy C-276™, Haynes HR-120™, Haynes HR-160™, Nimonic75™, Nimonic 86™, Haynes 556™, Incoloy 800™, Incoloy 800H™, Incoloy800HT™, Incoloy 801™, Incoloy 802™, MP35-N™ and Elgiloy™ can beutilized.

[0038] While the specification describes preferred designs and methods,those skilled in the art will appreciate the spirit and scope of theinvention with reference to the appended claims.

What is claimed:
 1. A pressure measuring device comprising: an elongatedtube comprising an opening, the elongated tube being slidably receivedin a tubular sheath, the tubular sheath comprising at least two spacedapart openings, the elongated tube being slidable within the tubularsheath thereby allowing the opening of the elongated tube to beselectively aligned with both openings of the tubular sheath.
 2. Thepressure measuring device of claim 1 wherein the elongated tube furthercomprises a closed distal end.
 3. The pressure measuring device of claim1 wherein the tubular sheath further comprises a closed distal end. 4.The pressure measuring device of claim 1 wherein the tubular sheathfurther comprises a proximal end and a distal end which define a firstlength, the elongated tube further comprises a proximal end and a distalend which define a second length, the second length being greater thanthe first length so that the proximal end of the elongated tube isdisposed outside of the proximal end of the tubular sheath, theelongated tube further comprising two markings, one of the markings ofthe elongated tube being aligned with the proximal end of the tubularsheath when the opening of the elongated tube is aligned with one of theopenings of the tubular sheath, the other of the markings of theelongated tube being aligned with the proximal end of the tubular sheathwhen the opening of the elongated tube is aligned with the other of theopenings of the tubular sheath.
 5. The pressure measuring device ofclaim 4 wherein the proximal end of the elongated tube is connected to apressure transducer.
 6. The pressure measuring device of claim 1 whereinthe tubular sheath has an inside surface and the elongated tube has anoutside surface, the elongated tube being frictionally received in thetubular sheath so that engagement between the inside surface of thetubular sheath and the outside surface of the elongated tubesubstantially prevents fluid communication through the tubular sheathand between the inside surface of the tubular sheath and the outsidesurface of the elongated tube.
 7. The pressure measuring device of claim1 wherein at least one of the elongated tube or tubular sheath comprisesa radiopaque marker at a distal end thereof.
 8. A pressure measuringdevice comprising a tubular sheath having an interior wall extendingthrough the tubular sheath thereby dividing the tubular sheath into twolumens, one of the openings of the tubular sheath being aligned with oneof the lumens, the other of the openings of the tubular sheath beingaligned with the other of the lumens.
 9. The pressure measuring deviceof claim 8 wherein at least one of the elongated tube or tubular sheathcomprises a radiopaque marker at a distal end thereof.
 10. A pressuremeasuring device comprising: an elongated tube comprising an opening andan outside surface, the elongated tube being slidably received in atubular sheath, the tubular sheath comprising at least two spaced apartopenings and an inside surface, the elongated tube being frictionallyreceived within the tubular sheath thereby allowing the opening of theelongated tube to be selectively aligned with both openings of thetubular sheath and so that engagement between the inside surface of thetubular sheath and the outside surface of the elongated tubesubstantially prevents fluid communication between the inside surface ofthe tubular sheath and the outside surface of the elongated tube andthrough the tubular sheath.
 11. The pressure measuring device of claim10 wherein the elongated tube further comprises a closed distal end. 12.The pressure measuring device of claim 10 wherein the tubular sheathfurther comprises a closed distal end.
 13. The pressure measuring deviceof claim 10 wherein the tubular sheath further comprises a proximal endand a distal end which define a first length, the elongated tube furthercomprises a proximal end and a distal end which define a second length,the second length being greater than the first length so that theproximal end of the elongated tube is disposed outside of the proximalend of the tubular sheath, the elongated tube further comprising twomarkings, one of the markings of the elongated tube being aligned withthe proximal end of the tubular sheath when the opening of the elongatedtube is aligned with one of the openings of the tubular sheath, theother of the markings of the elongated tube being aligned with theproximal end of the tubular sheath when the opening of the elongatedtube is aligned with the other of the openings of the tubular sheath.14. The pressure measuring device of claim 13 wherein at least onedistal end of the tubular sheath or elongated tube comprises aradiopaque marker at a distal end thereof.
 15. The pressure measuringdevice of claim 13 wherein the proximal end of the elongated tube isconnected to a pressure transducer.
 16. A pressure measuring devicecomprising: an elongated tube comprising an opening, the elongated tubebeing slidably received in a tubular sheath, the tubular sheathcomprising at least two spaced apart openings, the elongated tube beingslidable within the tubular sheath thereby allowing the opening of theelongated tube to be selectively aligned with both openings of thetubular sheath, the tubular sheath further comprising a proximal end anda distal end which define a first length, the elongated tube furthercomprising a proximal end and a distal end which define a second length,the second length being greater than the first length so that theproximal end of the elongated tube is disposed outside of the proximalend of the tubular sheath, the elongated tube further comprising twomarkings, one of the markings of the elongated tube being aligned withthe proximal end of the tubular sheath when the opening of the elongatedtube is aligned with one of the openings of the tubular sheath, theother of the markings of the elongated tube being aligned with theproximal end of the tubular sheath when the opening of the elongatedtube is aligned with the other of the openings of the tubular sheath.17. The pressure measuring device of claim 16 wherein the proximal endof the elongated tube is connected to a pressure transducer.
 18. Thepressure measuring device of claim 16 wherein the tubular sheath has aninside surface and the elongated tube has an outside surface, theelongated tube being frictionally received in the tubular sheath so thatengagement between the inside surface of the tubular sheath and theoutside surface of the elongated tube substantially prevents fluidcommunication between the inside surface of the tubular sheath and theoutside surface of the elongated tube and through the tubular sheath.19. The pressure measuring device of claim 16 wherein at least one ofthe elongated tube or tubular sheath comprises a radiopaque marker at adistal end thereof.
 20. A pressure measuring device comprising: anelongated tube comprising an opening, the elongated tube being slidablyreceived in a tubular sheath, the tubular sheath comprising an elongatedopening having a proximal portion and a distal portion, the elongatedtube being slidable within the tubular sheath thereby allowing theopening of the elongated tube to be selectively aligned along theelongated opening of the tubular sheath.
 21. The pressure measuringdevice of claim 20 wherein the elongated tube further comprises a closeddistal end.
 22. The pressure measuring device of claim 20 wherein thetubular sheath further comprises a closed distal end.
 23. The pressuremeasuring device of claim 20 wherein the tubular sheath furthercomprises a proximal end and a distal end which define a first length,the elongated tube further comprises a proximal end and a distal endwhich define a second length, the second length being greater than thefirst length so that the proximal end of the elongated tube is disposedoutside of the proximal end of the tubular sheath, the elongated tubefurther comprising two markings, one of the markings of the elongatedtube being aligned with the proximal end of the tubular sheath when theopening of the elongated tube is aligned with one of the openings of thetubular sheath, the other of the markings of the elongated tube beingaligned with the proximal end of the tubular sheath when the opening ofthe elongated tube is aligned with the other of the openings of thetubular sheath.
 24. The pressure measuring device of claim 23 wherein atleast one of the elongated tube or tubular sheath comprises a radiopaquemarker at a distal end thereof.
 25. The pressure measuring device ofclaim 20 wherein the proximal end of the elongated tube is connected toa pressure transducer.
 26. The pressure measuring device of claim 20wherein the tubular sheath has an inside surface and the elongated tubehas an outside surface, the elongated tube being frictionally receivedin tubular sheath so that engagement between the inside surface of thetubular sheath and the outside surface of the elongated tubesubstantially prevents fluid communication through the tubular sheathand between the inside surface of the tubular sheath and the outsidesurface of the elongated tube.
 27. A method for measuring pressure onopposing sides of an occlusion, the method comprising: providing apressure measuring device comprising an elongated tube comprising anopening, the elongated tube being slidably received in a tubular sheath,the tubular sheath comprising at least two spaced apart openings, theelongated tube having a proximal end connected to a pressure transducer,inserting the pressure measuring device into a vessel having anocclusion until one of the openings of the tubular sheath is disposed onone side of the occlusion and the other of the openings of the tubularsheath is disposed on an opposite side of the occlusion, aligning theopening of the elongated tube with the one of the openings of thetubular sheath, measuring the pressure at the one opening of the tubularsheath through the elongated tube, aligning the opening of the elongatedtube with the other of the openings of the tubular sheath, measuring thepressure at the other opening of the tubular sheath through theelongated tube.
 28. A method for measuring pressure on opposing sides ofan occlusion, the method comprising: providing a pressure measuringdevice comprising a tubular sheath comprising at least two spaced apartopenings and an interior wall extending through the elongated sheaththereby dividing the elongated sheath into two lumens, one of theopenings of the tubular sheath being aligned with one of the lumens, theother of the openings of the tubular sheath being aligned with the otherof the lumens, inserting the pressure measuring device into a vesselhaving an occlusion until one of the openings of the tubular sheath isdisposed on one side of the occlusion and the other of the openings ofthe tubular sheath is disposed on an opposite side of the occlusion,measuring the pressure through the one opening of the tubular sheath,measuring the pressure through the other opening of the tubular sheath.29. The method of claim 28 wherein the measuring steps are carried outsimultaneously.
 30. A method for measuring pressure on opposing sides ofan occlusion, the method comprising: providing a pressure measuringdevice comprising an elongated tube comprising an opening, the elongatedtube being slidably received in a tubular sheath, the tubular sheathcomprising an elongated opening, the elongated tube having a proximalend connected to a pressure transducer, inserting the pressure measuringdevice into a vessel having an occlusion until the elongated opening ofthe tubular sheath extends from one side of the occlusion to an oppositeside of the occlusion, aligning the opening of the elongated tube with aportion of the elongated opening of the tubular sheath disposed on theone side of the occlusion, measuring the pressure at the one side of theocclusion through the elongated tube, aligning the opening of theelongated tube with a portion of the elongated opening of the tubularsheath disposed on the opposite side of the occlusion, measuring thepressure at the opposite side of the occlusion through the elongatedtube.